“Central to Microsoft’s vision for Cortana is a Notebook feature that will allow Windows Phone users to control exactly what information is shared with the digital assistant,” Warren writes. “Notebook will allow the Cortana digital assistant to access information such as location data, behaviors, personal information, reminders, and contact information. We’re told it’s designed as a privacy feature to ensure Cortana doesn’t freely access information without a level of user control. While Cortana will learn things about users, it won’t store them in the Notebook without asking you, and any information that’s stored can be edited or deleted.”

Warren says that Microsoft’s biggest challenge will be making sure that Cortana’s voice commands work at least as well as Siri’s at launch and that they don’t require a rigid pattern of commands as the Xbox One’s Kinect sensor does at the moment. From there Microsoft will try to integrate Cortana into both Windows-based PCs and the Xbox One where it will serve as an all-purpose voice assistant for all Microsoft devices.